There are numerous applications where such a solution is optimal. A general application for machine builders is robot control. A common solution for pick-and-place applications is to have a proximity sensor fire when the desired object is in range and, as a result, the robot arm attempts to pick it up. This works well for a few applications, but some require more data than “Yes, an object is there,” or “No, an object isn’t there.” If, for example, one of the parts is rotated or skewed on the line at some point, the proximity sensor won’t detect it. The robot arm typically attempts to pick up a piece, expecting it to be in the same orientation as all of the previous pieces, often with subpar results. This can damage the product being picked up and the robot arm itself.
Designers add machine vision to many robotics applications as a form of guidance in place of simple proximity sensors. With a machine vision-based solution, the designer can send the robot arm the trigger to start the pick and place as well as the rotation and exact coordinates of the piece in question. This reduces missed parts, increases machine efficiency, and, in turn, saves the end user time, money, and headaches. Vision also reads 2D codes on parts to verify that the correct piece is picked up, and it ensures that nuts, bolts, and washers have been added correctly.
There are many other applications that are well-suited to having a machine vision system in place. These range from verifying labels on soda bottles to counting the number of pills that are poured into a bottle as it’s prepared for a pharmacy. Many no-contact measurements that need to be made can be performed with a machine vision system quite easily as well.
Once designers realize that they need to add machine vision to their new designs, the question comes back to which approach works best for them - an off-the-shelf machine vision system (like a smart camera) or a custom design. Cost is a major concern for many machine builders looking at off-the-shelf hardware. Some designers believe that they can save money by going with a custom design over an off-the-shelf solution. Yet, there are several costs associated with a custom design that many designers don’t realize until it’s too late. Understanding these costs up front makes a commercial off-the-shelf product a much more viable option.
One consideration is the time it takes to design a custom system versus the time it takes to implement a system using off-the-shelf parts. Putting together a custom vision sensor and setting up I/O on that sensor to communicate with the rest of the machine is a large task. Years go into the development of many custom designs, and time spent on engineers is expensive. This is often the highest cost associated with custom designs.
There are also hidden costs connected to custom designs that are not found in off-the-shelf hardware. Support is a large hidden cost. Designers not only have to support the operation of the machine built (which would be the case with both custom and off-the-shelf design), but they also have to support the intricacies of a custom design. When something in the custom design breaks, it may be costly to send someone to the site who has any idea what this custom design is doing or how to fix it. With off-the-shelf products like the smart camera, the support burden falls on the vendor of those products. If something happens to the machinery and the system stops functioning, off-the-shelf products offer a safety blanket on the support side.
Smart cameras are examples of commercial off-the-shelf products that can provide machine designers and engineers with the flexibility and power they need to meet the advanced application requirements set before them without having to turn to custom design. There will always be applications where custom design is necessary, but as off-the-shelf measurement and control hardware and software continue to become more powerful and lower in cost, they offer a much more practical solution.
This article was written by Matthew Slaughter, Vision Product Marketing Engineer at National Instruments, Austin, TX. For more information, visit http://info.hotims.com/15126-145.